Group programming ladder race - exercise set l2-002 linked list de duplication

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characteristic ： use Hash surface

#include<iostream>
#include<unordered_map>
#include<map>
#include<string>
#include<vector>
using namespace std;

struct ListNode {
    
	string addr;
	string next;
	int data;
};
int f_abs(int x) {
    
	if (x > 0)	return x;
	return -x;
}
int main() {
    
	unordered_map<string, ListNode> LinkList;		//Hash surface , Store the original linked list 
	vector<ListNode> Deleted;								// Store the deleted linked list nodes 
	map<int, int> nums;								// Mark whether this number exists 
	string head;
	int n;
	cin >> head >> n;
	string addr, next;
	int data;
	int cur = 0;
	for (int i = 0; i < n; i++) {
    
		cin >> addr >> data >> next;
		LinkList[addr].addr = addr;
		LinkList[addr].data = data;
		LinkList[addr].next = next;
	}
	LinkList["-1"];		//address=-1 As the termination condition of iteration 
	string pre_node = head;
	string node = LinkList[head].next;
	nums[f_abs(LinkList[pre_node].data)] = 1;		// First store the number of header nodes 
	while (node!= "-1") {
    
		int x = f_abs(LinkList[node].data);
		nums[x]++;
		if (nums[x]>1) {
    							// This number has appeared before 
			if (cur > 0) {
    					// The previous node of the node in the deleted node linked list needs special treatment , Change next value 
				Deleted[cur - 1].next = node;
			}
			Deleted.push_back({
     node, "-1", LinkList[node].data });		// Inserted nodes next The assignment is -1
			cur++;
			LinkList[pre_node].next = LinkList[node].next;
			node = LinkList[node].next;
		}
		else {
    
			pre_node = node;
			node = LinkList[node].next;
		}
	}
	//cout << endl;
	node = head;
	while (node != "-1") {
    
		cout << node << " " << LinkList[node].data << " " << LinkList[node].next<<endl;
		node = LinkList[node].next;
	}
	//cout << endl;  Output delete node 
	for (ListNode x : Deleted) {
    
		cout << x.addr << " " << x.data << " " << x.next << endl;
	}

	return 0;
}